Burman, Anton

Abstract [en]

In proximity to hydropower plants the watercourses usually vary substantially in channel bed topography, this means that stochastic large-scale roughness elements are apparent. The water level in the watercourses also vary heavily as a function of how much electricity that is being produced by the plant. This in turn can be troublesome for local fauna and flora. At Vattenfall Research and Development in Älvkarleby a channel aimed to emulate such watercourses has been built. The aim of this thesis is to gain further insight in flow phenomena as a function of the roughness and the water level by doing CFD simulations on the channel in Älvkarleby. In this work several contours for different water levels have been provided as well as double-averaged velocity profiles. Additionally the Gauckler-Manning Coefficient have been evaluated for all water levels. Furthermore the turbulent energy spectra is provided as a function of the water depth. The roughness was found to heavily contribute to the shape of the velocity field as well as the shape of the energy spectra. The work put forward in this thesis also highlights the need to properly resolve natural roughness in CFD and engineering applications.